A stroke occurs when a blood clot blocks a blood vessel, cutting off blood flow to the brain. The resulting death of brain cells can cause severe disability and death.

Ischemic heart disease, also called coronary artery disease, involves the hardening and narrowing of the arteries. Oxygen can’t reach the heart as effectively, which can weaken the muscle over time and end in heart failure. Ischemic heart disease also frequently leads to a heart attack, which is when a blood clot blocks the flow of blood to the heart.

The biggest risk factors for cardiovascular diseases are smoking, inactivity, and an unhealthy diet.

A global problem

Around the world, non-communicable diseases — the biggest of which are cardiovascular diseases, cancers, diabetes and chronic lung diseases — caused 68% of all deaths in 2012. Such diseases are often seen as the scourge of rich countries, but that’s not entirely true.

While non-communicable diseases caused 87% of deaths in high-income countries (like the US) in 2012 and just 37% of deaths in low-income countries (like Afghanistan), they are also leading causes of death in lower-middle income countries like Vietnam (57% of all deaths) and upper-middle-income countries like Brazil (81% of all deaths).

Curbing the number of people who die from ischemic heart disease and stroke around the world would save millions of lives. And the key tool in this fight will be focusing on prevention, not potential cures. There’s no real secret to saving these lives, which makes the task at hand both easier and harder than other public health challenges around the world.

“Unless current trends are halted or reversed, over a billion people will die from cardiovascular disease in the first half of the 21st century,” Anthony Rodgers, a researcher at the University of Auckland, New Zealand, said in a World Health Organisation report. “This would be an enormous tragedy, given that research in the last half of the 20th century showed that cardiovascular disease was largely preventable.“